1. Field of the Invention
The present invention relates to an electric element-embedded multilayer substrate, which is a multilayer substrate including an electric element embedded therein, and a method for manufacturing the same.
2. Description of the Related Art
Various types of electronic equipment, such as a mobile phone, tend to be downsized. Accordingly, electric elements such as circuit elements defining electronic equipment also tends to be downsized. Under such a circumstance, an electric element such as a circuit element is mounted on and integrated with a multilayer substrate, and used as an electric element-integrated multilayer substrate.
A typical electric element-integrated multilayer substrate 100Y will be described with reference to FIG. 13. Electric element-integrated multilayer substrate 100Y includes a multilayer substrate 10 formed by stacking a plurality of base material layers. In-plane wires 43 and interlayer wires 44 are formed within multilayer substrate 10. A front surface electrode 41 is formed on a front surface 11 of multilayer substrate 10. A back surface electrode 42 is formed on a back surface 12 of multilayer substrate 10.
In electric element-integrated multilayer substrate 100Y, an active element 20 and passive elements 24 are mounted as electric elements on the front surface 11 of multilayer substrate 10. The active element 20 and passive elements 24 are electrically connected to front surface electrode 41. The active element 20 is, for example, a semiconductor integrated circuit chip or the like. Passive element 24 is, for example, a capacitor chip, a resistor chip, or the like.
An electric element-embedded multilayer substrate 100Z as another typical electric element-integrated multilayer substrate will be described with reference to FIG. 14. In the electric element-embedded multilayer substrate 100Z, the active element 20 is mounted on a front surface 11 of multilayer substrate 10. Passive elements 24 are mounted within multilayer substrate 10. Passive elements 24 embedded in multilayer substrate 10 are electrically connected to in-plane wire 43.
A configuration having a passive element 24 embedded in multilayer substrate 10 is also disclosed in Japanese Patent Laying-Open No. 2006-121005. In an electric element-embedded multilayer substrate in Japanese Patent Laying-Open No. 2006-121005, a plurality of via hole conductors are arranged on upper and lower surfaces of an electric element. The plurality of via hole conductors are formed by charging a connection material into holes for a plurality of connection via hole conductors.
The plurality of via hole conductors are arranged at positions for regulating inclination of the electric element in a stacking direction, buckling of the via hole conductors having the connection material charged therein, and inclination of a conductor pattern in the stacking direction when a plurality of resin films (base material layers) are heated and pressurized. Japanese Patent Laying-Open No. 2006-121005 describes that, with the electric element-embedded multilayer substrate, reliability of electrical connection between the embedded electric element and the conductor pattern can be improved.
In the electric element-embedded multilayer substrate described in Japanese Patent Laying-Open No. 2006-121005, when the electric element is integrated with the multilayer substrate (base material layers), the electric element and the multilayer substrate (base material layers) are firmly fixed to each other.
When an impact stress is imposed on the electric element-embedded multilayer substrate due to an external cause, such as a dropping of the electric element-embedded multilayer substrate, the stress is also exerted directly on the embedded electric element. In addition, when a stress due to deformation such as warpage or bending, or a stress due to vibration and the like is exerted on the electric element-embedded multilayer substrate, these stresses are also exerted directly on the embedded electric element. By the action of the stress transferred to the electric element, defects such as damage to the electric element itself and disconnection of a wire pattern from the electric element may be caused.